OOM while increasing RAM to 4GB on DRA7x TI platform

I'm having issues on DRA7x based Android system where migrating from a
2GB RAM configuration to 4GB RAM has forced us to enable LPAE. In the
LPAE configuration, OOM killer causes issues as the system becomes
heavily loaded, but this issue does not occur on our more stable 2GB /
non-lpae baseline.

From what I understand, this is happening because we run out of low
memory. LPAE does place a marginally higher demand on lowmem in terms
of page tables, kernel size, etc. But still not sure of an exact root
cause.

Tuning/reducing vmalloc in the kernel command line seems to improve
the situation, but at the expense of introducing binder issues (since
binder uses vmalloc extensively).